Automatic regulator for electric circuits.



A. S. OUBITT. AUTOMATIC REGULATOR FOR ELECTRIC CIRCUITS.

APPLICATION FILED DEG.14, 1908.

'Patented Dec. 22, 1914.

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ARCHIIBALD S. CUBITT, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

AUTOMATIC REGULATOR FOR ELECTRIC CIRCUITS.

Specification of Letters Patent.

Patented Dec. 22, 1914.

Application filed December 14, 1908. Serial No. 467,505.

To all whom it may concern: Be it known that I, ARCHIBALD S. CUBrrT, a subject of the King of Great Britain, residing at Schenectady, in the county of Schenectady, State ofNew York,'- have invented certain new and useful Improvements in Automatic Regulatorstor Electric Circuits, of which the following is a specification'.

My invention relates to regulators for antomatically controlling electric circuits and more particularly to regulators similar to the Tirrill regulator, in which a resistance connected in the circuit is automatically short-circuited at suitable intervals.

which intermittently short-circuits some suitable regulating resistance in such a manner that the illumination from the lamps is practically constant in spite of variations in voltage on the line. A lamp may be used as the regulating resistance but the breaking of the lamp filament is apt to result in the destruction of the regulator, because as soon as the regulating resistance isbroken the contacts in the short circuit around the resistance are directly in series in the lighting circuit, and the arcing caused by intermittently opening and closing the lighting circuit is usually severe enough to destroy the contacts.

-The object of my invention is to protect the regulator in such a manner that the breaking of the regulating resistance will immediately reduce the current through the regulator to such appoint that the arcing at the contacts is not destructive, and in the preferred construction the breaking. ofthe resistance results in the regulator being permanently cut out of the lighting circuit. The regulator is generally used on street carsand in similar locations, where t is subjected to severe usage and neglect and a further object of my invention is to provide for the regulator a vibratory armature moved and replaced, and the tension of which can be easily varied to control the action of the regulator. I

In. carrying out my invention, the regulating resistance is connected in "series vwith the-circuit to be regulated, and the vibratory armature of the regulator is arranged to intermittently short-circuit the resistance and thereby control the circuit here the regulator is used to control the lighting circults on street cars, in which five lamps are usually connected in series between the trolley and the ground, one of the lamps is preferably utilized as a regulating resistance and is intermittently shortcircuited to malntain constant illumination from the re mainder of the lamps regardless of the variations in voltage on the line. The regulator is automatically and permanently cut out of circuit as soon as the regulating resistance or the filament of the regulating lamp is broken, this result being accomplished in any suitable manner, preferably by means of a heat responsive or thermal cutout mounted in such a relation to the vibratory contact that the radiant heat from the arcing at the vibratory contact will cause the cutout to operate and permanently open the circuit in case the arcing at the vibratory contact becomes abnormally severe. The

preferred form of thermal cutout comprises I a spring blade or similar resilient device normally tending to open the circuit and held in circuit. closing position by easily fusible metal placed in such relation to the vibrating contact that when the arcing at the contact becomes abnormal the fusible metal melts and releases the resilient device which then automatically opens the circuit. The action of the armature is improved and the defects of. the pivoted armature heretofore used are overcome by details of con struction which are more fully hereinafter explained.

My invention connection with the accompanying drawing, which illustrates one ofthe various forms in. which theinvention may be embodiedand in which i Figure 1 is a plan view of aregulator embodying my invention; Fig. 2 is an end view of the regulator shown in Fig}, with a portion of the base cut away to show the connections;- Fig. 3 is a view in perspective showing the vibrating armature and cutout;

and Fig. 4 is a diagrammatic view showing the regulator connected in the lighting circuit of the street car.. i

In the form of invention shown in the drawings, in which it is used for controlling the lighting circuit on a street car, the lamps 1 of the car'are connected in series between the trolley-and ground through a regulator comprising a regulating resistance 2, which may be of any suitable form, but is preferably an incandescent lamp. The regulating lamp 2 may be short-circuited by means of a low resistance shunt circuit comprising a fixed contact 3 mounted on the base of the regulator and cooperating with a vibratory contact 4 comprising a vibratory armature which, by its vibration, intermittently opens and closes the low resistance shunt circuit around the regulating lamp 2 and thereby intermittently cuts the regulating lamp into and out of circuit with the lamps 1.

As will be apparent from Fig. 4, the con nections are so arranged that when the vibratory contact is out of engagement with" the fixed contact and the shunt circuit is open,- the regulating lamp 2 is in series be] tween the other lamps' and the grdund; while, when the vibratory contact is in engagement with the fixed contact 3, the current flows through the lamps i and than directly through the shunt circuit to the ground. The circuit from both the regulating'resistance or lamp 2 and the vibratory contact 4 to the ground is completed through an electromagnet 5 which has its windings upon one leg of a U-shaped yoke 6 of iron. The vibratory contact 4: preferably conr prises an armature for the electromagnet mounted, as shown in Figs. 1 and 3, in such a position that it practically completes the magnetic circuit of the electromagnet by substantially closing the gap'between the ends of the U-shaped yoke 6. In the preferred construction the armature has a curved end 7 which overlaps and is practically parallel with an iron projection or support 8, mounted upon one leg'of theyoke 6 and provided with ears 9 which fit into notches on a spring blade 10 of non-magnetic material, and thereby interlock the support and the spring'blade so that the blade cannot be moved lengthwise or later ally but can be moved transversely and lifted out of position between the ears 9.on the support 8 As shown in Figs. 1 and 3, the vibratory contact 4: is formed, by riveting one end of the spring blade 10 to the vibratory armature and the otherend of blade is engaged by any suitable stop, such as an adjusting screw 11 threaded into a support on the leg of the yoke 6 and by means of which the spring blade 10 may be strained to hold the armature away from the electromagnet; The fixed contact 3 and theadjusting screw 11 form two stops which engage the vibratory contact on one side and the support or projection 8 forms a third stop which engages the vibratory contact. on

' the other side and between the first two stops, The three stops are in substantial alinement with one another and when the spring blade 10 is sprung'into position and interlocked with the projection 8, the blade is securely held against displacement until one of the stops is moved relatively to the others and out of alinement with them. The vibratory contact may be removed by loosening the adjusting screw 11 which allows the spring plate 10 to be moved horizontally clear ofthe projections 8 after which it may be lifted from the regulator. The strain tending to hold the armature againstthe fixed contact is adjusted by varying'the pressure exerted by the adjusting screw on the end or the springblade l0, and since the spring blade bends about the support 8 as a fulcrum, the difficulties incident to the use of pivots are avoided.

In a regulator constructed as above de- ;scribed and connected in the circuit as 2';

shown in Fig. 4, a relatively high voltage on the line will cause the vibratcry contact 4 to close the shunt circuit only at long intervals and then only momentarily, so that the regulating resistance is in series with the lamps 1 practically all the time, while low voltage causes the shunt circuit to be closed practically. all the time, whereby full line voltage is applied to the four lamps 1, and

when the voltage is between these limits the contact vibrates at a rateanclin amanncr which keeps the lamps 1 at substantially constant brilliancy. Under-all normal conditions, the amount of current which is controlled in the shunt circuit around the regulating resistance is small, but in case the regulating resistance is broken the vibratory contact is thrown into series with the lamps l and must then intermittently make and breakthe lighting circuit while the difference in potential between the contacts 3 and .4 is much higher: than when conditions are sire or thermal cutout'is used for opening the lighting circuit through the regulator and the lamps 1 and is mounted in such relat-ion to the vibratory contact 4; that the heat set up by the excessive'arcing at the vibratory contact causes the cutout to act. The preferred form of thermal cutout comprises a resilient spring 12 which is connected in the circuit and is held in circuit closing position by means of a :fusiblelink 13 extending across the ends of a notch in the blade 12 and engaging a hook 14 on the support for the fixed contact 3, thereby maintaining the fixed contact 3 in electrical connection with the regulating resistance or lamp 2 and the other lamps 1. The spring blade- 12 normally tends to spring up and thereby open the circuit and is restrained in circuit closing position only so long as the fusible link 13 is strong enough to hold the blade 12 in the position shownin Fig. 3.

As soon as the regulating resistance or regulating lamp is broken the current for the lamps 1 flows through the contacts 3 and 4 and the excessive arcing between the contacts 3 produces so much heat that the fusible link 13 quickly melts, whereupon the resilient blade 12 is released and springs up, quickly and permanently opening the circuit through the regulator and the lamps 1, and preventing damage to the regulator.

I It is desirable to provide some means for maintaining the circuit through the lamps 1 if the regulator should become disabled, since such an arrangement will permitthe car to be illuminated although the illumination will vary with the voltage on the line. Various means for accomplishing this. result may be used, but in the preferred construction the brokenregulating lamp is removed and the circuit is completed through another lamp which is connected in series with the four lamps 1, while the regulator is entirely disconnected. In order to enable the regulator to be disconnected, two sockets 15 and 16 are provided, each of whichhas the bottom cut away, as best shown in Fig.

1, and is traversed by contact blades 17 and 18, which tend to spring out of contact with each other and are out of contact with the sockets, as, is best shown in Fig. 4:. The socket 15 is connected to the vibratory contact 4 while the contactblade 17 is connected to the resilient blade 12 of the thermal cutout. Then the regulating lamp is screwed into. the socket 15, the center contact of the lamp engages the blade 17 which is thereby forced into engagement with the blade 18, as shown in Fig. 4, and the lamp completes a high resistance circuit from'the' vibratory.

contact 1 to the resilient blade 12, through which current must flow when the contacts 3 and 4 are separated. The socket 16 is connected to the grounded side of the circuit 1, while both the regulator and the socket 15 are entirely disconnected.

My invention may be embodied in many other forms than that shown and described, and I therefore do not wish to restrict it to the precise arrangement shown but intend to cover in the appended claims all changes and modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, an electric circuit comprising a resistance, electromagnetic means responsive to the voltage impressed uponsaid circuit for intermittently short-circuiting said resistance, said means comprising a .pair of contacts one of which is vibratory,

and means thermally responsive to the heat developed by excessive arcing of said contacts for permanently opening said short circuit.

2. The combination with an electric circuit, of a resistance in said circuit, a shunt path connected around said resistance comprising a pair of contacts, one of which is vibratory to intermittently short-circuit said resistance, and means thermally responsive to the heat developed by excessive arcing of said contacts for opening said shunt circuit.

3. In combination, an, electric circuit including one or more translating devices, a resistance, a regulator comprising anelectromagnetic vibrator the contacts of which are in shunt to said resistance and the electroi'nagnet of-which is in series with the contacts and the resistance'member, and means thermally responsive to the heat developed by excessive arcing of said contacts for opening said shunt circuit.

In witness whereof, I have hereunto set my hand this 11th day of December 1908.-

. ARCHIBALD S. CUBITT. Witnesses:

BENJAMAN B. HULL, HELEN Onronn. 

